1. Field of the Invention
The invention relates to laser shields, for protecting patients and physicians from misdirected or reflected laser beams during laser surgery. More particularly, it relates to particular types of laser shields for covering an endotracheal tube, for covering parts of the body of a patient, and for covering instruments and the like.
2. Description of Related Art
Previously, surgical sponge-like materials and metallic shielding materials have each been used individually for protecting patients and physicians against misdirected and reflected laser beams during laser surgery. However, the known systems have had disadvantages.
For example, for protecting the patient's body it is known to use wet, sponge-type materials. U.S. Pat. No. 4,520,814 of Weeks and U.S. Pat. No. 4,616,641 of Teeple mention a practice of using wet towels or gauze as a laser shield. However, both patents indicate that the practice does not work well, and may be unsafe for various reasons.
U.S. Pat. No. 4,604,998 of Bellina, and the Teeple patent mentioned above, both disclose combinations of metallic and non-metallic layers as a laser barrier.
U.S. Pat. No. 4,601,286 of Kaufman discloses various articles which are intended to be impervious to misdirected or reflected laser beams, comprising a hydrophilic gel and optionally, additives such as salts, colorants or medications. The articles include dressings, drapes, tapes and tubes. An adhesive backing or a metallic sheet backing with a reflective mirror finish may also be provided. This system, too, has disadvantages, which will be discussed further hereinbelow.
The hazards of endotracheal tube fire or perforation of the endotracheal tube cuff during laryngeal laser surgery are described in Forttenor et al., "Endotracheal Tube Safety During Laser Surgery," Laryngoscope 97: 919-921, August 1987, the disclosures of which are incorporated by reference herein. The authors measured perforation times of saline-soaked cottonoid pledgers, such as Surgical Patties, manufactured by Codman & Shurtleff, Randolph, Mass., and determined that saline-soaked pledgers are very efficient for protecting endotracheal tube cuffs. They also evaluated the safety and ignition properties of red rubber, silicone, polyvinyl chloride, and Xomed Laser-Shield.RTM. tubes by studying their perforation times and ignition properties under controlled oxygen supply conditions. They concluded that the Xomed Laser-Shield.RTM. tube had the highest ignition threshold of the four tubes tested. This tube includes a metallic coating, which the authors theorized advantageously improves its ignition threshold. The metallic coating also has a dull surface which prevents reflected energy from injuring surrounding tissues.
Hatzenbuhler et al., U.S. Pat. No. 4,558,093, discloses a surgical sponge and an endotracheal tube made of a special material, in which densely packed bubbles, which may be water bubbles, are encapsulated in a matrix of silicone. This special material is intended to terminate laser radiation. In the sponge, a layer of the special material is covered on both sides by layers of conventional sponge material. In the endotracheal tube, the tube itself is made of the special material.
U.S. Pat. No. 4,632,108 of Geil, U.S. Pat. No. 4,611,588 of Laptewicz et al., U.S. Pat. No. 4,489,722 of Ferraro et al., and U.S. Pat. No. 4,520,814 of Weeks disclose materials having a laser reflective additive (such as metal) for use as a laser barrier for an endotracheal tube (see Geil and Ferraro et al.), or as a laser shield to be applied to parts of the body (see Laptewicz et al. and Weeks). Weeks also discloses a laser shield comprising a rubber pad, which has a laser-reflective coating thereon, and over that, an outer layer of surgical gauze which is kept damp to provide further laser protection.
Also currently in use by physicians are metal tapes and metallized plastic tapes with adhesive backing, for being spirally wrapped on an object which is to be protected. These tapes have serious disadvantages, such as their high reflectivity, which can cause hazardous reflection of laser beams. Further, gapping occurs between the edges of the tape wrapped on the object, which exposes the object to laser beams and exposes the patient to sharp edges which can cause trauma to delicate throat tissues.
The disclosures of the above materials are incorporated herein by reference.